/**
 * Created by Administrator on 2017/6/22.
 */
var keyStr = "ABCDEFGHIJKLMNOP" + "QRSTUVWXYZabcdef" + "ghijklmnopqrstuv"
    + "wxyz0123456789+/" + "=";

function encode64(input) {

    var output = "";
    var chr1, chr2, chr3 = "";
    var enc1, enc2, enc3, enc4 = "";
    var i = 0;
    do {
        chr1 = input.charCodeAt(i++);
        chr2 = input.charCodeAt(i++);
        chr3 = input.charCodeAt(i++);
        enc1 = chr1 >> 2;
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
        enc4 = chr3 & 63;
        if (isNaN(chr2)) {
            enc3 = enc4 = 64;
        } else if (isNaN(chr3)) {
            enc4 = 64;
        }
        output = output + keyStr.charAt(enc1) + keyStr.charAt(enc2)
            + keyStr.charAt(enc3) + keyStr.charAt(enc4);
        chr1 = chr2 = chr3 = "";
        enc1 = enc2 = enc3 = enc4 = "";
    } while (i < input.length);

    return output;
}
function decode64 (input) {
	  var output = "";
	  var chr1, chr2, chr3;
	  var enc1, enc2, enc3, enc4;
	  var i = 0;
	  input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
	  while (i < input.length) {
	   enc1 = keyStr.indexOf(input.charAt(i++));
	   enc2 = keyStr.indexOf(input.charAt(i++));
	   enc3 = keyStr.indexOf(input.charAt(i++));
	   enc4 = keyStr.indexOf(input.charAt(i++));
	   chr1 = (enc1 << 2) | (enc2 >> 4);
	   chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
	   chr3 = ((enc3 & 3) << 6) | enc4;
	   output = output + String.fromCharCode(chr1);
	   if (enc3 != 64) {
	    output = output + String.fromCharCode(chr2);
	   }
	   if (enc4 != 64) {
	    output = output + String.fromCharCode(chr3);
	   }
	  }
	 /* output = _utf8_decode(output);*/
	  return output;
	 }
